Geometry of a seat tube on a beach bike

As i start to learn more about bikes, frames, etc I am paying more and more attention to my bike. It is a common beach bike but loads of fun to ride. I noticed that my seat tube is leans back much more than seat tubes of other bikes, maybe 20-25 degrees from being vertical. What effect does this have on the ergonomics of cycling? performance of the bike?

I think cruiser bikes have that relaxed geometry with a longer wheelbase so you can sit up more erect and enjoy the scenery. My bike is a cruiser/mt. bike hybrid (Giant Suede) with that type seat that slants back and is lower to the ground so you can touch your toes to the ground when stopped. I love the curviness of many of the cruiser frames because they are pleasing to the eye.

A Trek book I have shows cruisers like Wasabi, have a 72 -72.5 degree seat angle. Bikes like FX or Soho show 74 degree. Doesn't seem like that much difference but what do I know?